This proposal is to continue our studies of the behavioral effects of phencyclidine (PCP) in laboratory animals. PCP abuse remains a serious public health problem, and since this drug is a relatively recent entry into the drug abuse arena little is known of its effects. PCP has been shown to have some properties similar to psychotomimetic opioids such as cyclazocine. We will use PCP drug discrimination and intravenous drug self-administration to continue to explore this relationship. We will also compare the effects of PCP by smoking to the effects after parenteral administration. We will also compare the discriminative stimulus properties of PCP to PCP analogues and other drugs which may have PCP-like effects. These studies will help determine the structural requirements for PCP-like effects as well as provide information on the PCP-like abuse potential of other dissociative anesthetics. We have shown that chronic PCP administration in rhesus monkeys leads to physical and behavioral dependence. We will continue our studies of behavioral dependence by testing other drugs for cross dependence with PCP, comparing the dependence properties of PCP to other drugs of abuse, and establishing a rat model of PCP behavioral dependence. We will study the CNS mechanisms of action of PCP by direct intracerebral injection studies in rats. We propose to compare the effects of PCP to other drugs of abuse on social investigatory behavior of mice. Finally, we have found a very significant interaction between the effects of PCP and pentobarbital. We will continue our studies of PCP interactions with CNS depressants using isobolographic methods of analysis. The studies outlined in this proposal will provide both basic research on PCP and related compounds, and as well will address problems of more immediate application such as the conditions for PCP dependence and potentially harmful drug interactions.